81730357 has 4 divisors (see below), whose sum is σ = 82573036. Its totient is φ = 80887680.

The previous prime is 81730351. The next prime is 81730361. The reversal of 81730357 is 75303718.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 40436881 + 41293476 = 6359^2 + 6426^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81730357 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81730351) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 421194 + ... + 421387.

It is an arithmetic number, because the mean of its divisors is an integer number (20643259).

Almost surely, 2^81730357 is an apocalyptic number.

It is an amenable number.

81730357 is a deficient number, since it is larger than the sum of its proper divisors (842679).

81730357 is an equidigital number, since it uses as much as digits as its factorization.

81730357 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 842678.

The product of its (nonzero) digits is 17640, while the sum is 34.

The square root of 81730357 is about 9040.4843343706. The cubic root of 81730357 is about 433.9714227964.

The spelling of 81730357 in words is "eighty-one million, seven hundred thirty thousand, three hundred fifty-seven".